Your employer may have chosen not to book its employees on NK because of its weak schedule and IRROPS handling. While you may have found what you think saves money, in reality and over time, does not.
As to other situations, it will often be the case that there may be a cheaper way to do things, but a successful business focuses on the long-term, not the nickels & dimes.
Bear in mind that Concur is simply a piece of rules-enforcing software. It limits what you may book based on your employer's preferences. Thus, if you think that you are onto something, bring it to your CFO's attention. It has nothing to do with Concur.